The present invention relates generally to a novel resistance element, and more particularly, it relates to a resistance element such as an electrifying type resistance element or a thermistor which can be rapidly heated up to 1100.degree. C. or more within about 3 seconds without installing any control circuit applying a computer or the like and which is excellent in durability, i.e., which can withstand the repetition of the temperature rise and oxidation in a high temperature of about 1500 to 1550.degree. C. in air and which can be used for the ignition of a gaseous fuel or a liquid fuel.
Heretofore, for the ignition of gaseous and liquid fuels such as natural gas, propane gas and kerosene, current-carrying type resistance elements made of ceramics are generally used.
In order to withstand such rapid temperature-rise as to reach 1000.degree. C. or more within about 2 to 3 seconds and a high temperature of about 1500 to 1550.degree. C. in air, this type of resistance element for the ignition is required to have excellent thermal shock resistance and oxidation resistance.
To meet such a requirement, conventional ceramics resistance elements have been normally manufactured by embedding a heating element such as tungsten or tungsten carbide in silicon nitride (Si.sub.3 N.sub.4) and then sintering it.
In this case, however, silicon nitride can scarcely be sintered, and hence a rare-earth element is used as a sintering assistant to accomplish densification. However, when the rare-earth element is added, there occurs a problem that the oxidation resistance deteriorates at a temperature of 1400.degree. C. or more. Therefore, in practice, the upper limit of the usable temperature is set to 1400.degree. C., but when the rapid heating is carried out, a control circuit applying a computer or the like is required, which results in the increase of cost. In order to avoid such an increase of the cost, it is necessary to heighten the maximum reach temperature of the resistance element. In the conventional resistance element, however, it is difficult to further heighten the maximum reach temperature. In fact, in view of the cost and the oxidation resistance, a temperature-rise rate is unavoidably sacrificed.
In addition, a conductor layer which is used in the conventional resistance element is, for example, a heating element comprising tungsten or tungsten carbide mentioned above, but if a part of tungsten is silicified, there is a problem that the resistance of the conductor layer increases and its properties deteriorate.